VOLTCRAFT SWD Série Notice D'emploi page 35

Note on selection of the right lead battery
The converter can be operated at any direct voltage source, depending on type (12 or
24 V/DC). However, you need to consider that the voltage source can provide the res-
pective input current for the converter and is protected accordingly.
Preferably, converters are operated at lead batteries, since they can also provide short-
term power peaks.
Lead batteries are usually charged by chargers, generators or solar cells. These char-
gers are also decisive for lead battery regeneration. Recharging with solar cells takes
much longer due to the lower efficiency. This must be taken into account for power and
capacity determination.
The input current of a converter can be approximately calculated from the output power and efficiency.
Example calculation:
For example, a lead battery must be able to supply 55.6 ampere for a 600W converter in permanent ope-
ration. For a 1200W converter, these are 111 ampere already.
A fully charged 12V lead battery with a capacity of 70 Ah is able to deliver 55.6 ampere (600W) for a
period of time of approx. 1.2 hours (formula: battery capacity / power) without recharging. Where, e.g.,
two 100W light bulbs are lit for 8 hours, a battery capacity of at least 160 Ah is required for 12V.
The battery type used also influences the function. Solar batteries usually have a "softer" voltage than
starter batteries and thus have to be classified at least 15% higher than the desired application range as
starter batteries.
Input current = ------------------------------------------------
Input current = ------------------------------------------------ = 55,6 Ampere
Output power / efficiency
Input voltage
600 Watt / 0.90 (90%)
12 volt
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